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排序方式: 共有3258条查询结果,搜索用时 15 毫秒
31.
Susanna Monti Giovanni Barcaro Luca Sementa Vincenzo Carravetta Hans Ågren 《Nano Research》2018,11(4):1757-1767
The self-assembling properties, stability, and dynamics of hybrid nanocarriers (gold nanoparticles (AuNPs) functionalized with cysteine-based peptides) in solution are studied through a series of classical molecular dynamics simulations based on a recently parametrized reactive force field. The results reveal, at the atomic level, all the details regarding the peptide adsorption mechanisms, nanoparticle stabilization, aggregation, and sintering. The data confirm and explain the experimental findings and disclose aspects that cannot be scrutinized by experiments. The biomolecules are both chemisorbed and physisorbed; self-interactions of the adsorbates and formation of stable networks of interconnected molecules on the AuNP surfaces limit substrate reconstructions, protect the AuNPs from the action of the solvent, and prevent direct interactions of the gold surfaces. The possibility of agglomeration of the functionalized nanoparticles, compared with the sintering of the bare supports in a water solution, is demonstrated through relatively long simulations and fast steered dynamics. The analysis of the trajectories reveals that the AuNPs were well stabilized by the peptides. This prevented particle sintering and kept the particles far apart; however, part of their chains could form interconnections (crosslinks) between neighboring gold vehicles. The excellent agreement of these results with the literature confirm the reliability of the method and its potential application to the modeling of more complex materials relevant to the biomedical sector. 相似文献
32.
Michele Barletta Silvio Ranise Luca Vigan�� 《Service Oriented Computing and Applications》2011,5(2):105-137
The specification of distributed service-oriented applications spans several levels of abstraction, e.g., the protocol for
exchanging messages, the set of interface functionalities, the types of the manipulated data, the workflow, the access policy,
etc. Many (even executable) specification languages are available to describe each level in separation. However, these levels
may interact in subtle ways (for example, the control flow may depend on the values of some data variables) so that a precise
abstraction of the application amounts to more than the sum of its per level components. This problem is even more acute in
the design phase when automated analysis techniques may greatly help the difficult task of building “correct” applications
faced by designers. To alleviate this kind of problems, this paper introduces a framework for the formal specification and
automated analysis of distributed service-oriented applications in two levels: one for the workflow and one for the authorization
policies. The former allows one to precisely describe the control and data parts of an application with their mutual dependencies.
The latter focuses on the specification of the criteria for granting or denying third-party applications the possibility to
access shared resources or to execute certain interface functionalities. These levels can be seen as abstractions of one or
of several levels of specification mentioned above. The novelty of our proposal is the possibility to unambiguously specify
the—often subtle—interplay between the workflow and policy levels uniformly in the same framework. Additionally, our framework
allows us to define and investigate verification problems for service-oriented applications (such as executability and invariant
checking) and give sufficient conditions for their decidability. These results are non-trivial because their scope of applicability
goes well beyond the case of finite state spaces allowing for applications manipulating variables ranging over infinite domains.
As proof of concept, we show the suitability and flexibility of our approach on two quite different examples inspired by industrial
case studies. 相似文献
33.
Nordahl R Turchet L Serafin S 《IEEE transactions on visualization and computer graphics》2011,17(9):1234-1244
We propose a system that affords real-time sound synthesis of footsteps on different materials. The system is based on microphones, which detect real footstep sounds from subjects, from which the ground reaction force (GRF) is estimated. Such GRF is used to control a sound synthesis engine based on physical models. Two experiments were conducted. In the first experiment, the ability of subjects to recognize the surface they were exposed to was assessed. In the second experiment, the sound synthesis engine was enhanced with environmental sounds. Results show that, in some conditions, adding a soundscape significantly improves the recognition of the simulated environment. 相似文献
34.
We investigate the convergence of the price of anarchy after a limited number of moves in the classical multicast communication game when the underlying communication network is directed. Namely, a subset of nodes of the network are interested in receiving the transmission from a given source node and can share the cost of the used links according to fixed cost sharing methods. At each step, a single receiver is allowed to modify its communication strategy, that is to select a communication path from the source, and assuming a selfish or rational behavior, it will make a best response move, that is it will select a solution yielding the minimum possible payment or shared cost. We determine lower and upper bounds on the price of anarchy, that is the highest possible ratio among the overall cost of the links used by the receivers and the minimum possible cost realizing the required communications, after a limited number of moves under the fundamental Shapley cost sharing method. In particular, assuming that the initial set of connecting paths can be arbitrary, we show an $O(r\sqrt{r})We investigate the convergence of the price of anarchy after a limited number of moves in the classical multicast communication
game when the underlying communication network is directed. Namely, a subset of nodes of the network are interested in receiving
the transmission from a given source node and can share the cost of the used links according to fixed cost sharing methods.
At each step, a single receiver is allowed to modify its communication strategy, that is to select a communication path from
the source, and assuming a selfish or rational behavior, it will make a best response move, that is it will select a solution
yielding the minimum possible payment or shared cost. We determine lower and upper bounds on the price of anarchy, that is
the highest possible ratio among the overall cost of the links used by the receivers and the minimum possible cost realizing
the required communications, after a limited number of moves under the fundamental Shapley cost sharing method. In particular,
assuming that the initial set of connecting paths can be arbitrary, we show an
O(r?r)O(r\sqrt{r})
upper bound on the price of anarchy after 2 rounds, during each of which all the receivers move exactly once, and a matching
lower bound, that we also extend to
W(rk?{r})\Omega(r\sqrt[k]{r})
for any number k≥2 rounds, where r is the number of receivers. Similarly, exactly matching upper and lower bounds equal to r are determined for any number of rounds when starting from the empty state in which no path has been selected. Analogous
results are obtained also with respect to other three natural cost sharing methods considered in the literature, that is the
egalitarian, path-proportional and egalitarian-path proportional ones. Most results are also extended to the undirected case
in which the communication links are bidirectional. 相似文献
35.
36.
Luca Bertelli Shivkumar Chandrasekaran Frédéric Gibou B. S. Manjunath 《International Journal of Computer Vision》2010,90(3):267-282
In this paper we introduce novel regularization techniques for level set segmentation that target specifically the problem
of multiphase segmentation. When the multiphase model is used to obtain a partitioning of the image in more than two regions,
a new set of issues arise with respect to the single phase case in terms of regularization strategies. For example, if smoothing
or shrinking each contour individually could be a good model in the single phase case, this is not necessarily true in the
multiphase scenario. 相似文献
37.
38.
CAD based shape optimization for gas turbine component design 总被引:1,自引:0,他引:1
Djordje Brujic Mihailo Ristic Massimiliano Mattone Paolo Maggiore Gian Paolo De Poli 《Structural and Multidisciplinary Optimization》2010,41(4):647-659
In order to improve product characteristics, engineering design makes increasing use of Robust Design and Multidisciplinary
Design Optimisation. Common to both methodologies is the need to vary the object’s shape and to assess the resulting change
in performance, both executed within an automatic loop. This shape change can be realised by modifying the parameter values
of a suitably parameterised Computer Aided Design (CAD) model. This paper presents the adopted methodology and the achieved
results when performing optimisation of a gas turbine disk. Our approach to hierarchical modelling employing design tables
is presented, with methods to ensure satisfactory geometry variation by commercial CAD systems. The conducted studies included
stochastic and probabilistic design optimisation. To solve the multi-objective optimisation problem, a Pareto optimum criterion
was used. The results demonstrate that CAD centric approach enables significant progress towards automating the entire process
while achieving a higher quality product with the reduced susceptibility to manufacturing imperfections. 相似文献
39.
40.
Davide Anghinolfi Roberto Montemanni Massimo Paolucci Luca Maria Gambardella 《Computers & Operations Research》2011
The sequential ordering problem is a version of the asymmetric travelling salesman problem where precedence constraints on vertices are imposed. A tour is feasible if these constraints are fulfilled, and the objective is to find a feasible solution with minimum cost. 相似文献